N-(5-Amino-2-methylphenyl)-4-(3-pyridyl)pyrimidin-2-amine

The title compound, C16H15N5, crystallizes with two independent molecules (A and B) in the asymmetric unit. The dihedral angles of the pyrimidine ring with the benzene and pyridyl rings are 22.3 (1) and 53.2 (9)°, respectively, in molecule A, and 6.8 (1) and 11.6 (9)° in molecule B. The crystal packing is influenced by the collective action of weak intermolecular N—H⋯N hydrogen bonds, a π–π stacking interaction between neighbouring pyridyl rings of molecule A [centroid–centroid distance = 3.8395 (10) Å] and C—H⋯π interactions.

derivative that functions as a specific inhibitor of a number of tyrosine kinase enzymes, is a drug used to treat certain types of cancer and is used in treating chronic myelogenous leukemia (CML), gastrointestinal stromal tumors (GISTs) and a number of other malignancies. It is the first member of a new class of agents that act by inhibiting particular tyrosine kinase enzymes, instead of non-specifically inhibiting rapidly dividing cells. The crystal structures of related compounds, viz, 2amino-4-(4-pyridyl)pyrimidine and the 1:1 adduct with 4-aminobenzoic acid (Lynch & McClenaghan, 2001) (Hu et al., 2006), and 5-phenyl-2-(4-pyridyl)pyrimidine (Santoni et al., 2008) have been reported. In view of the importance of the title compound, its crystal structure is reported.
The title compound crystallizes with two molecules (A & B) in the asymmetric unit ( Fig. 1 & 2). The molecular structure consists of an amine nitrogen atom bonded to 5-amino-2-methylphenyl and 3-pyridyl-2-pyrimidine groups, respectively.
Bond lengths and bond angles are all within expected ranges (Allen et al., 1987). The dihedral angles between the mean planes of the 2-pyrimidine ring and the phenyl and pyridyl rings are 22.3 (1) and 53.2 (9)° in A, and 6.8 (1) and 11.6 (9)°i n B, respectively, presenting a much different structural arrangement in each of these molecules. Crystal packing is influenced by the collective action of weak intermolecular N-H···N hydrogen bond interactions (Table 1 and Fig. 3), π-π stacking interactions between nearby pyridyl A rings, [Cg1···Cg1 iv = 3.8395 Å; slippage = 1.520 Å; Cg1 is the centroid of C12A-C15A/N5A/C16A ring; symmetry code: (iv) -x, -y, 2 -z] and C-H···π interactions between the pyridyl A and phenyl A rings and between the phenyl A and B rings (Table 1).
A geometry optimized MOPAC PM3 (Parameterized Model 3) computational calculation (Schmidt & Polik, 2007), in vacuo, on each molecule separately supports these observations. The dihedral angle between the mean planes of the 2-pyrimidine ring and the phenyl and pyridyl rings change to 36.86, 40.06° in A and 0.00, 9.95° in B, respectively, providing support to these effects and contribute to the packing of these molecules into chains propagating along the [011].

Experimental
The title compound was obtained as a gift sample from INTERMED LABS PRIVATE LTD., Bangalore, India. X-ray quality crystals were grown from methanol: ethyl acetate (9:1) by slow evaporation of solvent mixture. The melting range was found to be 398-401 K.